Vertical shaft type darius windmill

Abstract

The present invention relates to a Darrieus windmill, and more specifically, to a vertical axis type Darrieus windmill that enables self-start in the low wind velocity range. The Darrieus windmill, in which a primary vertical shaft is rotated by the lift forces generated by primary blades, has a starting means for assisting the starting or rotation of the primary shaft at a low wind velocity. The present invention provides advantages of enabling self-start and rotation due to the lift generated by the blade in low wind velocity conditions and enabling the generation of rotating moments in any wind direction or wind velocity, thereby easily starting even in urban areas with very low wind velocities or large variations in wind direction, and thus enabling the generation of electricity over a wide range of wind velocities.

Description

RELATED APPLICATIONS[0001]This application is a 371 application of International Application No. PCT / KR2009 / 004313, filed Jul. 31, 2009, which in turn claims priority from Korean Patent Application No. 10-2008-0075358, filed Jul. 31, 2008, both of which are incorporated herein by reference in their entireties.TECHNICAL FIELD[0002]The present invention relates to a Drarrieus windmill, in more detail a vertical axis type Drarrieus windmill that can self-start in a low air speed range.BACKGROUND TECHNOLOGY[0003]In general, windmills convert rotational energy of blades rotated by natural wind into electricity by an electric generator.[0004]This is called wind power generation and they are classified into two types, according to the direction of rotational axis or the turbine, as HAWT (horizontal axis wind turbine) of which rotational axis is horizontal to the ground, and VAWT (vertical axis wind turbine) of which rotational axis is vertical to the ground.[0005]And according to the sourc...

AI Technical Summary

Benefits of technology

[0020]As described above, the present invention can self-start at low wind speed by the drag forces generated at the blades and can generate electricity.

[0021]Further, since it is possible to generate rotating moment with wind from any directions and any speed, the windmill can easily operate in city areas where wind speed is very low and wind directions vary rapidly, and can generate electricity in a wide range of wind speeds.

[0022]Further, the present invention can exploit the advantages of the Darrieus windmill having excellent aerodynamics characteristics in high wind speed region with high speed rotation made possible by means of lift forces.

[0023]Further, it is possible to connect the primary shaft with the secondary shaft, using a one-way clutch such that they rotate together at low wind speed and rotate independently from each other at high wind speed. Therefore, it is possible to significantly increase power generation capacity by individually connecting power generators to each shaft.

Problems solved by technology

One of the problems in the case of drag type of VAWT is that, when the tip speed ratio (ratio of tangential speed of blade and natural wind speed, TSP) reaches 1, the increase in the wind speed cannot increase the rotational speed and as the result, the generating efficiency is low.

In the lift type, when TSP is higher than 1, the aerodynamic efficiency of the turbine improves as the result of improved aerodynamic performance of the blades; however, when TSP is lower than 1, the aerodynamics performance of the windmill is worsened and the rotating moment of the blades are reduced.

And because of the reduced rotating moment, it becomes difficult to start the blades to rotate from the stationary condition.

However, in the above mentioned hybrid windmill, though the Savonius windmill can starts the DARRIEUS wind mill to rotate at low wind speed, as the rotating speed increases the Savonius windmill hinders the rotating movement of Darrieus windmill, and as the result, the efficiency of the whole system becomes lower than the case of Darrieus windmill only.

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